What is being called “Dragon’s Breath” happens when chewing extremely cold cereal puffs condenses moisture that looks like smoke when someone exhales, Suffolk County Commissioner of Health Services Dr. James Tomarken said in a statement.

The cereal, however, may still contain liquid nitrogen. That means it can harm skin and internal organs, and, if inhaled, can cause asphyxiation, Tomarken said.

Nassau’s Department of Health said it was not allowing restaurants to serve this food fad.

“We’ve only had a handful of requests to do that,” a spokeswoman said by telephone. “And they’ve been denied until it can be determined if this is a safe practice.”

She also said the department had not received complaints from the public “about any injury associated” with this technique.

Suffolk’s Department of Health Services said it issued its warning after recently receiving a memo from the state Department of Health.

The state agency said it issued the warning “out of an abundance of caution,” after local health officials inquired about Dragon’s Breath.

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“We are not aware of any injuries in New York State,” a state health spokesman said by email.

Liquid nitrogen is not dangerous when used in some foods, such as ice cream, he said. “It disperses as it is mixed and freezes the ice cream, leaving behind little to no residue,” he said.

Dave Zollo, who owns Freezology, an ice cream shop in Patchogue, said cooling the cream so swiftly with liquid nitrogen creates “a really fine crystal; you get almost a gelato-like texture.”

Suffolk quoted the state memo outlining the severity of Dragon’s Breath hazards: “Instances of frostbite and tissue damage have been reported when residual liquid nitrogen is left in the serving cup.”

To protect consumers’ fingers, some vendors sell the cereal treat — sometimes found at fairs — with skewers.

However, all of the liquid nitrogen must be removed from the cereal — which can absorb it — before it is eaten.

“Ingestion of liquid nitrogen can cause severe damage to the mouth, esophagus, and stomach,” the memo said.

A Suffolk health spokeswoman said the liquid nitrogen technique was new to them. “In Suffolk County, to our knowledge, no one that we’re aware of is serving this; no one has been reported to us that has been hurt,” the spokeswoman said.

This might not even be the latest incarnation of the Dragon Breath craze that has spread on social media around the world for the past few years.

Another newer, hazardous fad also is making the rounds, said Islandia fire marshal Michael Zaleski.

“Let me ask you this: ‘You really think it’s OK to take a 25-pound propane tank, turn it upside down, put your lips to it and then light it with a lighter?’ ” he asked rhetorically.

Yet this is the technique his 14-year-old nephew asked him about trying two weeks ago, he said.

“A lot of people have been asking, ‘Is it really dangerous?’ ” said Zaleski, who compared it to the cinnamon-swallowing and Tide-pod-laundry-detergent-ingesting videos previously popular.

“The consequences” of the propane stunt, he said, “are that you can literally sear your lungs, wind up with respiratory and trachea burns that can be fatal.”